1. Field of the Invention
This invention relates to an apparatus and method for monitoring cleaning processes for medical devices. More particularly, this invention relates to an apparatus and method capable of determining when the device is sufficiently cleaned so that the device can be sterilized.
2. Description of the Related Art
Adequate cleaning of contaminated medical instruments and devices is essential for safe disinfection and sterilization. Failure to adequately remove inorganic and organic soil derived from body liquids and tissues can impede the effectiveness of subsequent sterilization procedures resulting in infections. Additionally, remaining foreign materials introduced during subsequent invasive procedures can produce pyrogenic reactions that can impede healing.
It is preferable to use machine processes for cleaning which have been validated for this purpose in a clinical setting and which preferably accomplish sterilization during or after the cleaning cycle. The selected cleaning processes should produce satisfactory results under certain test and field conditions as well as ensure that adequate cleaning is performed under exceptional circumstances and conditions.
It is not only necessary that a high level of cleaning performance be achieved, but also that the cleaning system be capable of adapting to the specific needs of particular medical instruments and devices. The ideal cleaning system will be capable of adequately cleaning medical instruments and devices with long, narrow, inaccessible orifices such as those found on flexible endoscopes as well as the inner surfaces of take-apart, modular instruments. In the case of sophisticated instruments which may no longer be able to be taken apart in the future, adequate cleaning performance must also be achieved.
A variety of cleaning machines and related apparatus have been developed for medical instruments and devices.
U.S. Pat. No. 3,640,295 to Peterson describes an ultrasonic cleaner and surgical instrument carrying case, which is useable separately and apart from or in combination with the ultrasonic cleaner, the ultrasonic cleaner including within at least one sink and oscillatable cradle which may carry the instrument case during the ultrasonic cleaning process. A pump and filter are additionally provided as part of the ultrasonic cleaner to circulate a cleaning fluid within the sink of the ultrasonic cleaner and to remove particles and other matter from the fluid. The Peterson ""295 patent does not address standards or quality of cleaning.
U.S. Pat. No. 3,957,252 to Storz and assigned to Storz-Endoskop GmbH discloses an apparatus for cleaning medical instruments. The apparatus disclosed in the ""252 Storz patent pertains to support means provided for mounting an ultrasonic oscillator for engaging washing water in a conventional sink, for use in cleaning medical instruments. The focus of the invention is to eliminate the need for an independent special ultrasonic cleaning tank.
U.S. Pat. No. 4,064,886 to Heckele and assigned to Riwoplan Medizin-Technische Einrichtungs-Gesellschaft GmbH discloses an apparatus for cleaning endoscopes, comprising a holder device, a cylindrical cleaning container, time control means for placing the holder device under timed control and a rotatable mounting for the holder device. The object of the invention is to enable fast and automatic cleansing and sterilization of endoscopes, which can be carried out without damaging the endoscopes. Again, the invention does not address standards or quality of cleaning.
U.S. Pat. No. 4,710,233 to Hohmann et al. and assigned Siemens Aktiengesellschaft discloses a method and apparatus for cleaning, disinfecting, and sterilizing medical instruments with a sequence of method steps performed in a single apparatus. The invention discloses a complicated method and apparatus. The method steps include precleaning the instruments in a container containing a first fluid bath subjected to ultrasonic energy for a period of time T1, subsequently emptying the first fluid bath from the container and replacing it with a second fluid bath containing a cleaning agent and sodium chloride, fine cleaning and disinfecting the instruments by subjecting the second bath to ultrasonic energy for a time period T2 and circulating the second bath through an electrolytic cell having a voltage applied to the electrodes to create an electrolytic disassociation therein, then emptying the second bath and replacing it with a rinse bath, rinsing instruments for a time period T3 by subjecting the rinsing bath to ultrasonic energy and circulating the rinsing bath through the electrolytic cell subsequently emptying the rinse bath, and drying the instruments by means of heated air. Thus, the Hohmann ""233 invention is designed to provide adequate cleaning and sterilization of medical instruments, however, this is achieved with an expensive and complicated apparatus and method.
U.S. Pat. No. 5,032,186 to Childers, et al. and assigned to American Sterilizer Company discloses a method and apparatus for washing and sterilizing hospital or laboratory materials. The invention involves loading a chamber with items to be washed, filling the chamber to a predetermined level with a washing fluid, controllably injecting a steam or an air-steam mixture into the chamber during the filling of a chamber with the washing fluid, the steam being injected in a turbulent manner to create a washing action and to begin heating the washing fluid, and continually injecting steam into the chamber after the chamber is filled to the predetermined level so as to subject the items to a washing action. After the washing phase, the chamber is drained, the items are rinsed and the chamber is drained again. Sensors are employed to monitor the operating parameters of the apparatus. Sensors are utilized for controlling the operation of the spray nozzles and the steam injectors such that steam is controllably injected into the chamber after a certain point during the filling of the chamber with the washing fluid to create a washing action and to begin heating the washing fluid. Again, this invention does not provide means to assure adequacy of cleaning.
U.K. Patent Application No. 2,248,188 A to Parker, et al. and assigned to Keymed Ltd. discloses a method and apparatus for cleaning and disinfecting medical instruments. The method and apparatus of the invention are particularly suited for cleaning and disinfecting endoscopes. The method comprises the steps of placing an instrument in an enclosure and subjecting the instrument to a cleaning phase in which a cleansing solution is applied to the surfaces of the instruments, a disinfection phase in which a disinfectant solution is applied to the surfaces of the instrument, a rinsing phase in which a flushing solution is applied to the surfaces of the instrument, a purging phase in which a volatile liquid is applied to the surfaces of the instruments and a drying phase in which a drying gas is passed over the surfaces of the instrument. The cleaning phase is described as a period sufficient to thoroughly clean the endoscope both externally and internally. Again, the invention does not address means for assuring adequacy of cleaning.
None of the aforementioned apparatus and methods provide the means for assuring adequacy of cleaning of a medical device or instrument. Therefore, a need remains for an improved apparatus and method for monitoring cleaning processes for medical devices.
Before a detailed discussion of the present invention is given, it should be mentioned that certain terms have been used in this disclosure in their broadest meaning. Thus, the term xe2x80x9csterilizationxe2x80x9d or xe2x80x9csterilizexe2x80x9d as used herein also include the meaning of disinfection. Similarly, the terms xe2x80x9ccleaningxe2x80x9d and xe2x80x9ccleaning liquidxe2x80x9d as used herein also cover rinsing or a rinsing liquid.
The invention relates to an apparatus and method for monitoring a cleaning process for a medical device, capable of determining when the device is sufficiently clean so that the device can be sterilized.
A soil detector is provided in the apparatus of the invention, which may utilize a variety of detection technologies for monitoring cleaning, alone or in combination. Generally, the detection technology is selected from the group consisting of ion-selective electrodes, conductivity, spectrophotometry, ion chromatography, capillary electrophoresis, high performance liquid chromatography, liquid chromatography, cyclic voltammetry, radioactivity, quartz crystal microbalance and other gravimetric techniques, infra-red spectroscopy and other spectroscopic techniques.
The apparatus of the invention may employ detection technology wherein the detection technology is suitable for detecting the presence of the soil on a surface of a medical device. The detection technology which is suitable for detecting the presence of soil on a surface of a medical device may operate without contacting the surface of the device. Alternatively, detection technology suitable for detecting the presence of soil on the surface of a medical device may operate via direct surface contact Alternatively, an indirect detection technology may also be employed. This approach employs the same physical-chemical detection technologies previously mentioned for other approaches. However, the medical device itself is not monitored for the degree of cleaning. Rather, a soil-deposited standard is inserted in the apparatus and monitored in place of the medical device itself. A correlation between the degree of cleaning of the soiled device to be cleaned and the degree of cleaning of the soiled standard can be established, so that when the standard is cleaned to certain degree the sufficient cleaning of the device to be cleaned is achieved.
Thus, in one aspect of the present invention, there is provided an apparatus for monitoring a cleaning process for a medical instrument. The apparatus comprises a cleaning chamber for receiving and cleaning the instrument with a cleaning liquid. A soil detector is coupled to the cleaning chamber and adapted to provide an indication of the amount of the soil on the instrument. The soil detector is at least partially isolated from the chamber so that access to the detector by the cleaning liquid is controllable. The soil detector can be moveable, and by moving the detector it can be made in or out of fluid communication with the chamber. The soil detector may comprise an electrode located in an enclosure, and the enclosure is so coupled to the chamber that the cleaning liquid has controllable access to the enclosure.
In another aspect of the present invention, there is provided a method for cleaning and sterilizing a soiled medical device. The method comprises the steps of: a) providing a cleaning chamber for receiving the soiled device; b) providing a soil detector coupled with the cleaning chamber; c) introducing a cleaning liquid into the cleaning chamber; d) cleaning the soiled device in the cleaning chamber; e) exposing the detector to the cleaning liquid so as to measure the amount of soil removed from the soiled device; f) determining that a sufficient amount of the soil has been removed from the soiled device so that the soiled device can be sterilized; and g) sterilizing the soiled device. Preferably, the detector is at least partially obstructed from the cleaning liquid during step d). Exposing the detector to the cleaning liquid and obstructing the detector from the cleaning liquid can be achieved by moving the detector in and out of fluid communication with the chamber, or by locating the detector in an enclosure so coupled to the chamber that the cleaning liquid has controllable access to the enclosure.
In another aspect of the present invention, there is provided an apparatus for monitoring a cleaning process for a soiled medical instrument. The apparatus comprises a chamber for receiving and cleaning the instrument. An enclosure is in controllable fluid communication with the chamber. A chemical source is coupled to the enclosure for providing a chemical capable of reacting with the soil of the instrument to generate a detectable signal in the enclosure. A detector for detecting the signal is provided with the apparatus. The chemical can be selected from Hg(SCN)2, OPA(o-phthatic dialdehyde+Triol), Bromcresol purple (C12H16Br2O5S9), biuret reagent, and Microprotein-PR. The apparatus may further comprise a light source for sending a light beam through the cleaning liquid in the enclosure to the detector. The enclosure may be separated from the chamber by a valve. The chamber has an inlet and an outlet, and a second detector can be coupled to the inlet, and the first detector and the enclosure are coupled to the outlet.
In another aspect of the present invention, there is provided a method for cleaning and sterilizing a soiled medical device. The method comprises the steps of: a) providing a cleaning chamber for receiving the soiled device; b) providing a chemical source coupled to an enclosure in controllable fluid communication with the cleaning chamber, the source containing a chemical capable of reacting with the soil on the device to generate a detectable signal; c) introducing a cleaning liquid into the cleaning chamber; d) cleaning the soiled device in the cleaning chamber; e) releasing the chemical from the source into the enclosure; f) detecting the signal generated through reaction between the chemical and soil in the cleaning fluid to determine if a sufficient amount of soil has been removed form the device; and g) sterilizing the device. A portion of the cleaning fluid can be introduced into the enclosure before the chemical is released into the enclosure, and before the introduction of the portion of the cleaning liquid, the enclosure can be separated from the cleaning chamber so that substantially there is no fluid communication therebetween. The signal can be color or absorption at certain wave length.
In another aspect of the present invention, there is provided an apparatus for monitoring a cleaning process for a medical instrument. The apparatus comprises a chamber for receiving and cleaning the instrument. A standard containing a predetermined amount of soil is positioned in the chamber or in controllable fluid communication with the chamber. A detector adapted to provide an indication of the amount of the soil on the standard is coupled to the apparatus. The apparatus may comprises a cleaning/rinsing system which is adjustable so as to change relative cleaning efficiency in different locations of the apparatus. The standard can be positioned so that the instrument is cleaned more efficiently than the standard. The indication can be a signal such as concentration of the soil in a liquid used to clean the device, electrical potential of a liquid used to clean the device, conductivity, transparency to certain wave length, or color of a liquid used for the cleaning. Preferably, the standard may comprise a surface covered with the soil. An additional light source may be provided which generates a light beam of a predetermined wave length which travels through the standard and reaches the detector. The standard can be placed in an enclosure in controllable fluid communication with the chamber. The enclosure can be provided with a chemical source capable of controllably releasing a chemical to the enclosure, which chemical reacts with the soil removed from or remained on the standard to generate a detectable signal. The detector may comprise an electrode located in the enclosure.
In another aspect of the present invention, there is provided a method for cleaning and sterilizing a soiled medical device. The method comprises the steps of: a) providing a chamber for receiving the soiled device; b) providing a soiled standard coupled to the chamber; c) introducing a cleaning liquid into the chamber; d) cleaning the soiled device and the soiled standard; e) measuring the amount of soil removed from the soiled standard; f) determining that a sufficient amount of the soil has been removed from the soiled standard so that the soiled device can be sterilized; and g) sterilizing the soiled device. Preferably, the cleaning step comprises exposing the standard to a cleaning environment as effective or less effective than that to which the soiled device is exposed, and the determining step comprises determining that the soiled standard has been cleaned to a predetermined level. The soiled standard can be more heavily soiled or more difficult to clean than the soiled device. The method may further comprise measuring soil level of the cleaning liquid before the liquid is introduced into the chamber. Step e) may comprise measuring an inorganic soil such as inorganic electrolytes, alkaline and alkaline earth salts, inorganic metal-containing compounds and other inorganic compounds present in the human body which may come in contact with a medical device, and/or measuring an organic soil such as proteins, glycoproteins, lipoproteins, mucous, amino acids, polysaccharides, sugars, lipids, glycolipids, other organic compounds present in the human body which may come in contact with a medical device, microorganisms and viruses. The step of measuring the amount of soil removed from the soiled device can be conducted by detecting soil remained on the soiled standard or soil removed from the soiled standard and contained in the cleaning liquid. Preferably, the soiled standard is placed in an enclosure in controllable fluid communication with the chamber, so that by controlling the degree of fluid communication between the chamber and the enclosure, the relative cleaning efficiency of the chamber and the enclosure can be adjusted. Step e) may comprise measuring the soil level of the cleaning liquid in the enclosure.
In another aspect of the present invention, there is provided an apparatus for monitoring a cleaning process for a medical instrument. The apparatus comprises a cleaning chamber for receiving and cleaning the instrument, and at least a first soil detector and a second soil detector adapted to provide an indication of the amount of soil removed from or remained on the instrument. The first and second soil detectors are placeable in fluid communication with the cleaning chamber. The first and the second soil detectors may be selected from ion-selective electrodes, conductivity, spectrophotometry, ion chromatography, capillary electrophoresis, high performance liquid chromatography, liquid chromatography, radioactivity, gravimetry, infra-red spectroscopy, potentiometry and turbidimetry. One of the soil detectors may be adapted to detect inorganic soil, and the other to detect organic soil. One detector can be located adjacent to an inlet of the cleaning chamber, and the other detector is located adjacent to an outlet of the cleaning chamber. The apparatus may further comprise a second chamber in fluid communication with the cleaning chamber, and one detector is located in the second chamber, one in the cleaning chamber, so that the measuring results from the two chambers can be compared and used to determine the degree of cleaning.
In still another aspect of the present invention, there is provided a method for cleaning and sterilizing a soiled medical device. The method comprises the steps of: a) providing a cleaning chamber for receiving the soiled device; b) introducing a cleaning liquid into the cleaning chamber; c) cleaning the soiled device in the cleaning chamber; d) measuring the amount of soil removed from the soiled device with at least two detectors; e) determining that a sufficient amount of the soil has been removed from the soiled device so that the soiled device can be sterilized; and f) sterilizing the device. Step d) may comprise measuring soil level of the cleaning liquid with a first detector before the cleaning, and measuring the soil level of the cleaning liquid with a second detector during or after cleaning. Step e) may comprise comparing the soil level of the cleaning liquid measured by the first detector with the soil level of the cleaning liquid measured by the second detector. If the difference between the two soil levels is within a predetermined range, the sufficient amount of soil has been removed from the soiled device. Step d) may comprise measuring, with one detector, an inorganic soil such as inorganic electrolytes, alkaline and alkaline earth salts, inorganic metal-containing compounds and other inorganic compounds present in the human body which may come in contact with a medical device, and measuring, with another detector, an organic soil such as proteins, glycoproteins, lipoproteins, mucous, amino acids, polysaccharides, sugars, lipids, glycolipids, other organic compounds present in the human body which may come in contact with a medical device, microorganisms and viruses. The step of measuring the amount of soil removed from the soiled device may be conducted by detecting soil remained on the soiled device or soil removed from the soiled device and contained in the cleaning liquid.
The apparatus of the present invention as discussed above may further comprise a vacuum pump connected to the chamber, so that the chamber also functions as a vacuum chamber.
The apparatus of the present invention as discussed above may further comprises a sterilization system.
In the method according to the present invention, the sterilizing step can be conducted by a vapor phase procedure.
In the method according to the present invention, the cleaning liquid can comprise a liquid sterilization agent, such that the cleaning step and the sterilizing step are conducted simultaneously.
The method according to the present invention may further comprise a vacuum drying step.